ISO noise at ISO 200?

[jeffreyw]

Hello everyone!

I recently bought a new Nikon d300s with a 18-200mm VR II (The latest model). A couple days back I brought it with me to the beach to take a few shots of my gf and her friends. When I came home and uploaded them to my computer and viewed them at 100% I noticed something strange in the clouds, I had A LOT of noise. I quickly checked if I accidentally bumped my ISO up or something, but no, it said ISO 200. When I examined the other picture, especially dark (underexposed) areas, they all had noise in them.

Unfortunately I am at work and haven't got any sample pictures with me, but when I mentioned noise I meant quite a lot of visible noise. I was shooting all my pictures in RAW with a high quality JPEG. The RAW file had quite a lot of noise in the picture but the JPEGs were just simply aweful.

Now I was wondering if anyone knew if it was "normal" to have quite some noise in darker areas of your picture and/or with the Nikon d300s?

Thanks in advance,
Jeffrey

P.S. most pictures were taken between 50-105 mm

[sybren]

I'm by no means someone with knowledge about Nikon noise levels, but I do know that you'll probably get more response if you include some examples.

[jeffreyw]

I will once I get home. I was only wondering if anyone might have heard/seen something similar

[wulf]

My guess is that the pictures were underexposed or at least had very dark areas. That's where I've seen artifacts of the digital process, even at low ISOs.

The reason is that each pixel is represented by a mix of RGB values. For an 8-bit image (eg. JPEG), each one can be given a value of 0-255 (over 16 million combinations). However, if an area is dark, the range, and thus number of combinations, is restricted. If the total brightness (which comes from adding the RGB values) is very low, eg. 10, there are not many choices to get there. R10, G0, B0? R8, G1, B1? etc. Therefore, there is more chance that neighbouring pixels will be forced to identical or very similar values, creating larger visual blocks which we perceive as a form of noise.

Wulf

[jeffreyw]

I understand what you're saying wulf, the thing is I shoot in 12-bit RAW (which is 68,719,476,736 color combinations). Anyhow, I will upload pictures soon to get a clearer idea of what I mean with the amount of noise.

[wulf]

You will still have a problem in very dark areas even though a 12 bit image will be vastly more sensitive to small changes. Show us a image to make your problem clearer though (probably a crop of a particulary troublesome area to help us focus and fit within the posting limits).

Wulf

[vandergus]

I think it's important to realize just how big you're viewing the image when you look at a D300 file at %100 on a monitor. It's equivalent to a 43" X 29" print. That's enourmous. Are you planning on printing at anywhere near this size? If not, you may be getting worked up over nothing.

Secondly, you may be able to detect noise but is it actually harming the image? Is it getting in the way and detracting from the overall viewing experience?

Thirdly, some amount of noise is a good thing. It helps to smooth the tonal graduations in an image and prevent the fake watercolor look.

All I'm trying to say is be careful when viewing images at %100 as it's not often the best way to evaulate what the image will look like in its final application, whether it be a print or electronic display.

[jdepould]

Step one is to make sure auto-ISO is off, because if it isn't, then you aren't shooting at ISO200.

Second thing to check is active d-lighting. If you have it set to auto or high, that may be the culprit.

If you post samples with EXIF, we can probably help you a lot more.

My D300 (non-s) is clean all the way up to 800 with good exposure, and 1600 isn't bad. The newer s-type has slightly better noise handling (same chip, newer software), so it's probably a setting.